Electromagnetism

Electricity and magnetism share certain characteristics and together create certain effects. To talk about the two together, we use the word "electromagnetism." The study of electromagnetism is part of physics. Marshalled electromagnetic forces have many applications in technology.

Relationship Between Electricity and Magnetism

Electricity involves two charges that attract or repel, and magnetism involves poles that attract or repel. Both electrical charges and magnets possess fields around them. A changing magnetic field creates an electric field, and a changing electric field creates a magnetic field. This creates electromagnetic waves that travel through space.

History

Even in the 17th century, researchers saw the similarities between electricity and magnetism and wanted to make a connection between them. In 1820 Danish scientist Hans Christian Oersted found a connection. He found that a current-carrying wire produced a magnetic field when he moved it. The discovery showed that the motion of the charges produces a magnetic field. In 1831 Michael Farady discovered that motion is needed to produce an electric current with a magnet.

Electromagnetic Waves

Electromagnetic waves are produced by oscillating electric and magnetic fields. The fields are perpendicular to each other and also the direction the wave is moving. When the waves have a fixed frequency, they possess crests and troughs and are symmetrical. Their wavelength is the distance between two identical spots on the wave, say the distance between the top of one wave and the top of the next wave.

Electromagnetic Spectrum

Electromagnetic radiation can be arranged in a spectrum according to wavelength, frequency and energy. Frequency is the number of times a motion occurs over a set period of time, usually measured in hertz (Hz), which is cycles per second. Moving from longest wavelengths to shortest, the order on the spectrum is radio waves, then microwaves, infrared radiation, visible light, ultraviolet rays, X-rays and gamma rays.

Applications

The fact that an electric field is produced by a changing magnetic field and vice versa allows electromagnetism to provide a foundation for a lot of technology that relies on the phenomena, for instance, electrical generators that create electricity. Electromagnetism is used in medicine, computer memory storage and television technology. Electromagnetism underlies the applications of electrical engineering.